Juvenile diabetes is a major cause of morbidity, mortality, and great emotional suffering. Additionally, psychosocial factors and emotional stress are thought to be influential regarding adherence to treatment regimens as well as complications in the course of the illness. The study of juvenile diabetes is appropriate as a model for understanding the interactions of biomedical and psychosocial factors in affecting medical and psychological well-being. Patients in the study are 60 metabolically labile diabetic patients (brittles), a comparison group of 60 non-brittle diabetics, and a comparison group of 60 normal subjects. Patients are between ages 10-22 years. In this project, the states and changes in the psychosocial and biological systems are viewed as interdependent and influencing each other at all times. Data are being collected in both systems. Emphasis also is placed on strategies of coping with life stress and social support as a moderator of stress. Attempts are being made to differentiate sub-sets of patients for whom psychosocial and biomedical variables cluster and, in turn, to trace the health consequences for individuals with differing patterns of response.